哪位dalao帮忙看一下为什么出现这个错误啊，是不是洛谷OJ出问题了？只要是CF和UVA的题，都提交不了

总是给我报CE，错误代码如下

编译信息
远端 OJ 尚未返回编译信息
Can't compile file:
program.cpp: In function 'int main()':
program.cpp:7:5: error: 'cin' was not declared in this scope
     cin>>t;
     ^~~
program.cpp:7:5: note: suggested alternative:
In file included from C:/Programs/mingw-w64/lib/gcc/i686-w64-mingw32/6.4.0/include/c++/i686-w64-mingw32/bits/stdc++.h:75:0,
                 from program.cpp:2:
C:/Programs/mingw-w64/lib/gcc/i686-w64-mingw32/6.4.0/include/c++/iostream:60:18: note:   'std::cin'
   extern istream cin;  /// Linked to standard input
                  ^~~
program.cpp:12:23: error: 'sort' was not declared in this scope
         sort(a+1,a+n+1);
                       ^
program.cpp:12:23: note: suggested alternative:
In file included from C:/Programs/mingw-w64/lib/gcc/i686-w64-mingw32/6.4.0/include/c++/algorithm:62:0,
                 from C:/Programs/mingw-w64/lib/gcc/i686-w64-mingw32/6.4.0/include/c++/i686-w64-mingw32/bits/stdc++.h:65,
                 from program.cpp:2:
C:/Programs/mingw-w64/lib/gcc/i686-w64-mingw32/6.4.0/include/c++/bits/stl_algo.h:4727:5: note:   'std::sort'
     sort(_RandomAccessIterator __first, _RandomAccessIterator __last,
     ^~~~
program.cpp:14:9: error: 'cout' was not declared in this scope
         cout<<ans<<endl;
         ^~~~
program.cpp:14:9: note: suggested alternative:
In file included from C:/Programs/mingw-w64/lib/gcc/i686-w64-mingw32/6.4.0/include/c++/i686-w64-mingw32/bits/stdc++.h:75:0,
                 from program.cpp:2:
C:/Programs/mingw-w64/lib/gcc/i686-w64-mingw32/6.4.0/include/c++/iostream:61:18: note:   'std::cout'
   extern ostream cout;  /// Linked to standard output
                  ^~~~
program.cpp:14:20: error: 'endl' was not declared in this scope
         cout<<ans<<endl;
                    ^~~~
program.cpp:14:20: note: suggested alternative:
In file included from C:/Programs/mingw-w64/lib/gcc/i686-w64-mingw32/6.4.0/include/c++/istream:39:0,
                 from C:/Programs/mingw-w64/lib/gcc/i686-w64-mingw32/6.4.0/include/c++/sstream:38,
                 from C:/Programs/mingw-w64/lib/gcc/i686-w64-mingw32/6.4.0/include/c++/complex:45,
                 from C:/Programs/mingw-w64/lib/gcc/i686-w64-mingw32/6.4.0/include/c++/ccomplex:39,
                 from C:/Programs/mingw-w64/lib/gcc/i686-w64-mingw32/6.4.0/include/c++/i686-w64-mingw32/bits/stdc++.h:52,
                 from program.cpp:2:
C:/Programs/mingw-w64/lib/gcc/i686-w64-mingw32/6.4.0/include/c++/ostream:590:5: note:   'std::endl'
     endl(basic_ostream<_CharT, _Traits>& __os)

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